TARDIGRADE KEY

Tag: Superfamily Macrobiotoidea

Richtersius

Richtersia from Pilato & Binda 1987: “Macrobiotidae; tubo boccale rigido provvisto di sbarretta di rinforzo ventrale la cui porzione anteriore è rilevata a formare una cresta mediana assai pronunciata recante un vistoso processo ad uncino (*); dorsalmente la porzione anteriore del tubo boccale presenta una cresta mediana molto sviluppata con un processo ad uncino ancor […]

Diaforobiotus

Genus description from Guidetti et al. 2016: “Peribuccal lamellae (ten) and ventral lamina present. A dorsal thickening present in the anterior portion of the buccal tube, in conjunction with a large tooth on the internal surface of the tube. Some strong, scattered round teeth present posterior to the second band of teeth of the buccal […]

Richtersiusidae

Richtersiidae from Guidetti et al. 2016: “Double claws Y-shaped, with the two branches forming an evident common tract of variable length. Large teeth on all lunules. Buccal tube with ventral lamina and a cuticular thick on the anterior, dorsal wall of the buccal tube (which can form a large apophysis). Absence of transverse crests in […]

Paramurrayon

Genus description from Guidetti et al. 2022: “Small claws of the Murrayon type (=pullari type): basal section of the double claw appears as a trapezoidal lamina (in lateral view); primary and secondary branches similar in length and joined to each other for a very short portion, forming an acute angle (V-shaped); lunules present. Three macroplacoids […]

Murrayon

Genus description from Bertolani & Pilato 1988: Macrobiotidae con unghie di tipo pullari, ossia con la porzione basale a laminetta trapezoidale e i due rami divergenti fin dalla base (unghie a V) e formanti un angolo acuto; le basi delle due unghie di ciascuna zampa sono indipendenti, ossia non collegate fra loro da alcun ispessimento […]

Macroversum

Genus description from Pilato & Catanzaro 1988: “In ciascuna diplounghia il ramo principale ed il secondario, saldati rigidamente fra loro come in tutti i Macrobiotidae, divergono l’uno dall’altro fin dalla base. La porzione basale è assottigliata come nelle unghie di tipo hufelandi, a formare un esile peduncolo. Il ramo secondario è più corto del principale […]

Dactylobiotus

Genus description from Schuster et al. 1980: “Ten buccal lamellae present; without peribuccal papulae. Buccal tube short, rigid, without spiral thickenings. Buccal mucrones and interior buccal baffles present. Pharynx contains apophyses and macroplacoids, but no microplacoids or septulum. Cuticle without pores; two dorso-lateral spines present. Two double claws of each leg of similar size and […]

Murrayidae

Murrayidae from Bertolani et al. 2014: “Double claws V-shaped or L-shaped, with the two branches diverging immediately after a short common basal section; ventral deep indentation on the ventral lamina; buccal tube completely rigid; epicuticular layer with pillar-like structures, sometime visible only at ultrastructural level.” generic key: Guidetti R, Giovannini I, Del Papa V, Ekrem […]

Xerobiotus

Genus description from Bertolani & Biserov 1996: “Claws of Xerobiotus-type, i.e., with a basal tract small and thin, not separated by a septum from the rest of the claw, and therefore without a distinct basal peduncle, with the secondary branch inserted on the main branch. Bucco-pharyngeal apparatus of Macrobiotus-type, with lamellae around the mouth and […]

Tenuibiotus

Genus description from Pilato & Lisi 2011: “Genus of Macrobiotidae characterised by claws of the tenuis-type, i.e. with a stalk, a long common section in which primary and secondary branches are joined, and distal free sections of both the secondary branch (shorter than the primary) and primary branch forming almost a right angle. The bucco-pharyngeal […]

Claw Symmetry Relative To Median Plane Of Leg?

Image from Bingemer J, Hohberg K. 2017. An illustrated identification key to the eutardigrade species (Tardigrada, Eutardigrada) presently known from European soils. Soil Organisms. 89 (3): 127-149.

Stylet Support Insertion Point As Percentage Of Buccal Tube Length

Stylet support insertion point = ss divided by Buccal tube length, as %. Note anterior measurements begin at anterior margin of stylet sheaths, ss is centred where stylet supports reach buccal tube (this requires a good dorsal or lateral view for proper measurement)

Image from Tumanov DV. 2006. Five new species of the genus Milnesium (Tardigrada, Eutardigrada, Milnesiidae). Zootaxa. 1122: 1-23.

Buccal Tube Long, Mouth At Anterior Of A Protrusible Snout

Images from Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.

Pharyngeal Tube With Spiral Reinforcement

Images from Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.

Peribuccal papillae?

Images from Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.

(Lateral) cephalic papillae, peribuccal papillae, Milnesiidae - type claws, exceptionally wide (and usually short) buccal tube?

Cephalic image modified from Nelson DR, Guidetti R, Rebecchi L. 2009. Tardigrada. Ch. 14 in Ecology and Classification of North American Freshwater Invertebrates, Thorp JH, Covich AP (eds.), 3rd ed.

Claw image modified from Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.

Pharyngeal tube flexible?

Note: in a tardigrade with snout extended, the flex of the pharyngeal tube may not be obvious.

Images from Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.

Serrated / dentate cuff / collar on legs IV

Left image from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

Right Image from Richters F. 1926. Tardigrada. in Krumbach T. 1927. Handbuch der Zoologie, 3rd band, Walter de Gruyter & Co.

Leg sensory structures

Typically papilla on leg IV (se4 in image) and variable shape on leg I

Image from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

Trunk appendages

Appendages (after Cirrus A) labeled according to plate … B (Scapular plate), C (First segmental plate), D (Second segmental plate), E (terminal plate). “B” is lateral, “Bd” is dorsal

Be careful! There can be great variability within a population, with individuals (especially juveniles) lacking some appendages. When in doubt, focus on other characters first!

Left image from Ramazzotti G, Maucci W. 1983. Il phylum Tardigrada(III edizione riveduta e aggiornata). English translation by C. W. Beasley, 1995. Memorie dell’ Istituto Italiano di Idrobiologia 41: 1-1012.

Right image cropped from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

Cirrus A form

Images modified from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

Lower image (Mopsechiniscus) modified from du Bois-Reymond Marcus E. 1944. Sobre tardigrados brasileiros. Communicaciones Zoologicas del Museo de Historia Natural de Montevideo. 1(13): 1-19 plus plates.

Terminal / caudal plate with two notches?

Images modified from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

First image (Echiniscus) modified from Richters F. 1926. Tardigrada. in Krumbach T. 1927. Handbuch der Zoologie, 3rd band, Walter de Gruyter & Co.

Inner & outer buccal cirri present

Image modified from Nelson DR, Guidetti R, Rebecchi L. 2009. Tardigrada. Ch. 14 in Ecology and Classification of North American Freshwater Invertebrates, Thorp JH, Covich AP (eds.), 3rd ed.

Pseudosegmental plate between last medial plate & terminal plate?

Note on 2nd image, what you see before the terminal plate is either no plate, or a full-width medial plate; don’t confuse the latter with a pseudosegmental plate!
Also, sometimes the pseudosegmental plate is paired, like segmental plates II & III. It’s still pseudosegmental!

Images from Clifford HF. 1991. Aquatic invertebrates of Alberta. University of Alberta Press, Alberta, Canada.

Segmental plates larger than intersegmental?

Image modified from Lindahl & Balser (1999), http://www.iwu.edu/~tardisdp/Keypage35.html

Any Paired Plates?

Modified from Lindahl K, Balser S.  1999. Key to tardigrade genera [Internet]. Available from: https://sun.iwu.edu/~tardisdp/Keypage33.html